Fuel System troubles???????

I am having fuel starvation troubles on my 70 Blazer. It has an aftermarket huge tank. Under hard acceleration, the fuel pressure will drop to 0, and in the high rpms, fall on its face. I have replaced pump, put an electric back at tank, only to still have problem. I blew into the tank to blow off sock hoping this was it, still no fix. I put my lawnmower tank in back at first, same problem. I can see my line from front to back, looks fine, this is about all I can guess it is now. Anyone had similar problems?

I had a similar problem, at first it wasn't getting enough fuel on hill climbs. Then on a hill climb it died completely and wouldn't restart. We changed the fuel filter by the tank it didn't help at all then we pulled out the filter inside the carb (quadrajet) and it ran just like it's supposed to drove to the parts store and replaced the filter and 1000 miles later I've had no issues. Not sure if this is the same problem your having but it could only be a few things.

I had identical problems with my 72 K5. I also run a 38 gallon aftermarket tank, and thought the problem was in the pick up within the tank, so I bypassed the tank to a Jerry can, but still had low fuel pressure. Replaced my fuel pump too, but didn't solve the problem. Checked and changed all filters, checked all soft and hard fuel lines, replaced all the soft line, but still had the problem. Out of a last ditch attempt to isolate the problem, I bypassed the hard fuel line from the tank to pump with some soft line, and it solved the problem! The moral of the story is that even if your hard line looks OK, it may still be rotted, or split. Being that it is on the vacuum side of the pump, a leak will not be readilly obvious.

You mentioned that it would be on the vacuum side... I have an electric pump mounted at tank, would this make any difference? I had just about come to the same conclusion, just hadn't tried it yet. Thanks for the help. Tommy

You also have to make sure the pump is mpunted lower than the tank. Electric pumps are pushers, not pullers, so if the fuel cant easily get to it, it will starve for fuel. We use to have this problem on a s10 4x4 drag race truck. If it sat on an incline betwen races it would not get any fuel. But if we blew air into the tank to force fuel it would be fine.

I had this problem on a Trans Am once. After many dollars I found a soft rubber fuel line was sucking closed. I would replace all with new rubber. You might even want to increase th size of you fuel line from tank to pumps.

With the way that these things get used and if the thing's ever been subjected to trash gas from some gas station that needed its tanks replaced badly (i.e. water contamination in the fuel), the hard line has probably become plaqued up with calcification or rust. I'm actually amazed that my POS Blazer doesn't have this problem since most everything else was screwed up with it when I got it.

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